Removal of 2,4-D herbicide in soils using a combined process based on washing and adsorption electrochemically assisted

Abstract

Abstract In this work, it is presented an innovative soil remediation technology consisting of the combination of soil washing, GAC adsorption and electrolysis. This technology is applied for the remediation of soil polluted with herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The new combined process involves three steps into a single chamber: first step is related to the washing of soils using groundwater as soil washing fluid, the second step is related to the herbicide removal from the produced soil washing effluent by adsorption onto granulated active carbon and the third step is the use of electrolysis to oxidize the 2,4-D and provide bubbles that enhance the mixing and separation by dissolved gas flotation. All processes are studied alone and in combination. The obtained results pointed out the possibility for total removing of the herbicide content in the contaminated soil, simultaneously to the herbicide removal contained in soil washing effluent, which become ready to be recycled as a fresh soil washing fluid. The proposed combined treatment for complete decontamination of soils polluted with 2,4-D herbicide was successfully tested for 0.1 kg soil, contained 20 mg herbicide per kg of soil, using 1 dm3 of synthetic groundwater as washing effluent and 10 g GAC, and passing through this mixture an electrical current of 0.5 A, during 2 h.